Overview of Acceleration and Routing mode for WXA

03/26/2020 1250 13101

DESCRIPTION:
This article contains an overview of acceleration and routing mode for the WXA series.

RESOLUTION:

Feature/Application:

This document gives a quick overview of TCP & USMB acceleration when the SonicWall appliance is configured in "Routed Mode".

There exists an issue when Web-Cache is enabled in Routed Mode. Click here to know more about the issue and its workaround.
: Acceleration is not supported in dynamic/protocol routing

Figure 1 Test network example

Above is the test network setup.

Notes

• Traffic is going from LAN to WAN so by default traffic will be applied NAT
• If traffic has NAT applied then it will not be TCP Accelerated.

Figure 2 NAT policies disabled on NSA3600

Figure 3 NAT policies disabled on NSA250M

SonicOS uses the routing table to enable acceleration on a route.

Figure 4 NSA3600 routing table

Route number 2 is the route with acceleration enabled.

Traffic from the "X3 Subnet" to the "RemoteSubnet (172.16.0.0/24)" use "X1 Default Gateway". I use the address object name "RemoteSubnet" on the NSA3600 and on the NSA250M. However on the NSA3600 the address object "RemoteSubnet" is the X3 Subnet of the NSA250M. Inversely on the NSA250M the address object "RemoteSubnet" is the X3 Subnet of the NSA3600.

You can use any address object name you wish.

Figure 5 Route #2 on NSA3600

Figure 6 NSA250M routing table

Figure 7 NSA250M Route #1

Same as the NSA3600, traffic from the "X3 Subnet" to the "RemoteSubnet (172.16.3.0/24)" use "X1 Default Gateway".

How to debug

Is traffic being forwarded to the WXA?

Couple of ways to figure this out

• Look at the TCP Accel or WFS "Statistics" tab are the traffic counts increasing. May have to wait up to 10 minutes depending on throughput rate.
• You can look at "Connection Monitor" and find connections with "src iface" the same as the WXA dedicated interface.

Figure 8 NSA250 X2 connection from WXA

• You can also use "Packet Monitor" to capture traffic on the WXA interface.

Traffic is not being forwarded?

• Look at the logs for both WXA and NSA.
• Look at the "Debug"" stats on the NSA "diag" page.

Figure 9 The show debug stats displays connections forwarded to WXA

Figure 10 Debug statistics

Figure 11 Zero the statistics

When you make a change you may wish to zero the statistics and then check again which counter is increasing.

Web caching stops working in Route Mode due to Web Proxy NAT policy being lower than Routed Mode NAT policy.

If an interface is to be configured to be Routed Mode, the default outbound NAT Policy must be disabled and a new "no-NAT" NAT Policy created. This can be done either manually or by enabling Express Mode Settings on the Advanced tab of the interface.



When Express Mode Settings is enabled, the SonicWall auto-creates the No-NAT NAT Policy.



When WXA Web Cache is enabled, three NAT policies are auto-created to divert traffic to the WXA appliance.





If Express Mode Settings is configured before enabling Web Cache, the auto-created no-NAT NAT Policy takes precedence over the Web Cache NAT policies thus rendering it ineffective.



This prevents Route Mode subnet traffic from being cached by WXA.

As a workaround, perform the following steps:

1. Login to the SonicWall management GUI
2. Navigate to the Interfaces page.
3. Click on Configure on the interface in Routed Mode.
4. Disable the check box under Express Mode Settings.
5. Click on OK to save.

This will delete the auto-created outbound no-NAT NAT policy.

1. Click on Configure on the Routed Mode interface.
2. Click on the Advanced tab.
3. Enable check box under Express Mode Settings.
4. Click on OK to save.

This will re-create the outbound no-NAT NAT policy with a lower priority than the Web Cache NAT policy.